The present invention relates generally to a transport refrigeration unit for cooling a refrigerated container which includes a pair of transverse fans with substantially parallel axes that are driven by a simplified drive mechanism and which discharges air drawn through the condenser outside of the refrigeration unit.
A transport refrigeration unit is typically utilized to cool a refrigerated container of a truck or trailer which transports refrigerated cargo, such as frozen food. The refrigeration unit is typically secured to the front wall of the truck or trailer at a main support frame. In a prior transport refrigeration unit, both axial and transverse fans are utilized to draw air through the evaporator and condenser. As the axes of the heat exchanger fans are not parallel, a complex drive system is utilized to drive the fans, increasing the complexity of the drive system.
Air drawn through the evaporator in a prior transport refrigeration unit must also make a 180xc2x0 turn from entry into the evaporator to exit into the refrigerated container. As the air is required to make several turns, there is additional friction and loss of energy, reducing the capacity of the refrigeration system.
Additionally, in a prior transport refrigeration unit, air drawn through the condenser is directed over the compressor which is located in the lower section of the refrigeration unit. As the compressor heats during operation of the refrigeration unit, the heated discharged air from the condenser, which is cooler than the compressor, provides additional cooling of the compressor and drive package (motor and/or engine plus motor).
The transport refrigeration unit of the present invention cools a refrigerated container which transports refrigerated goods, such as frozen foods. Air drawn through an inclined evaporator by a transverse fan is cooled and released at the top of the refrigerated container, cooling the cargo contained in the refrigerated container. Preferably, the evaporator is angled approximately 25xc2x0 to 45xc2x0 from the trailer wall to increase the area of heat transfer.
Air is drawn through the condenser by a larger transverse fan and discharged outside of the refrigeration unit in the direction of road airflow during forward vehicle movement. Preferably, the condenser transverse fan is approximately 1.2 to 1.5 times the size of the evaporator transverse fan as there is a larger amount of air passing through the condenser.
The axes of the heat exchanger transverse fans are substantially parallel to the axis of a motor shaft which drives the fans. As all the axes are substantially parallel, one continuous belt passing over the heat exchanger fans pulleys and the motor shaft pulley drives the fans, simplifying the drive mechanism of the refrigeration unit.
The refrigeration unit further includes a partition including extensions located between the evaporator and the condenser to provide insulation. The extensions are positioned between the wall of the vehicle and the frame of the refrigeration unit to provide further insulation and preferably includes corrugations to further seal air flow.
Accordingly, the present invention provides a transport refrigeration unit including a simplified drive system which drives a pair of heat exchanger fans.